Linked Life Data

16914435

Source:http://linkedlifedata.com/resource/pubmed/id/16914435

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2006-8-17
pubmed:abstractText
Exposure of the early gestation ovine fetus to exogenous glucocorticoids induces alterations in postnatal cardiovascular physiology, including hypertension. To determine whether autonomic function and systemic vascular reactivity are altered by in utero programming before the development of systemic hypertension, we examined arterial baroreflex function and in vivo hemodynamic and in vitro vascular responses to vasoactive agents in 10- to 14-day-old newborn lambs exposed to early gestation glucocorticoids. Dexamethasone (Dex, 0.28 mg.kg-1.day-1) or saline was administered to pregnant ewes by intravenous infusion over 48 h beginning at 27 days gestation (term 145 days), and lambs were allowed to deliver (n=6 in each group). Resting mean arterial blood pressure (MABP; 77+/-1 vs. 74+/-3 mmHg) and heart rate (HR; 249+/-9 vs. 226+/-21 beats/min) were similar in Dex-exposed and control animals, respectively. The arterial baroreflex curve, relating changes in HR to MABP, was significantly shifted toward higher pressure in the Dex-exposed lambs although no change in the sensitivity (gain) of the response was seen. In vivo changes in blood pressure in response to bolus doses of ANG II (20, 50, and 100 ng/kg) and phenylephrine (2, 5, and 10 microg/kg) were similar in the two groups. However, Dex lambs displayed greater decreases in MABP in response to ganglionic blockade with tetraethylammonium bromide (10 mg/kg; -30+/-3 vs. -20+/-3 mmHg, P<0.05) and greater increases in MABP after nitric oxide synthase blockade with NG-nitro-L-arginine (25 mg/kg; 23+/-3 vs. 13+/-2 mmHg, P<0.05) compared with control lambs. By in vitro wire myography, mesenteric and femoral artery microvessel contractile responses to KCl were similar, whereas responses to endothelin (in mesenteric) and norepinephrine (in femoral) were significantly attenuated in Dex lambs compared with controls. Femoral vasodilatory responses to forskolin and sodium nitroprusside were similar in the two groups (n=4). These findings suggest that resetting of the baroreflex, accompanied by increased sympathetic activity and altered nitric oxide-mediated compensatory vasodilatory function, may be important contributors to programming of hypertension.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0363-6119
pubmed:author
pubmed:issnType
Print
pubmed:volume
291
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
R481-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Early gestation dexamethasone alters baroreflex and vascular responses in newborn lambs before hypertension.
pubmed:affiliation
Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA. jeffrey-segar@uiowa.edu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural